1. Field of the Invention
The present invention relates to an air bag in use for a head protection air bag device carried on a motor vehicle. More particularly, the invention relates to an air bag in use for a head protection air bag device in which the air bag is stored along the peripheral edge of the upper fringe of an opening on the indoor side in a state that the air bag is covered with an air bag cover and folded.
The present application is based on Japanese Patent Application No. Hei. 2000-219791, which is incorporated herein by reference.
2. Description of the Related Art
In this type of head protection air bag device, as described in Unexamined Japanese Patent Publication No. Hei. 10-138858, the air bag, while being folded, is stored along the peripheral edge of the upper fringe of an opening on the indoor side in a state that the air bag extends from the front pillar to the rear part beyond the center pillar.
At the roof side rail on the upper fringe of an opening on the indoor side, the air bag folded is stored while being covered with a door of an air bag cover, which is located on the lower edge of the roof head lining. The air bag forcibly opens the door of the air bag cover, and develops and inflates. At the center pillar, the air bag develops and inflates so as to cover the indoor side of the center pillar garnish disposed on the indoor side of the center pillar.
In the conventional head protection air bag device, the lower fringe of the door of the air bag cover is connected to the upper fringe of the pillar garnish of the center pillar in a state that it is bent to the cabin outside. When the air bag presses the door to open, the door temporarily bends such that it climbs over the upper edge of the pillar garnish, and opens. Accordingly, the door does not open smoothly. In this respect, there is room for improvement on how to quickly complete the developing and inflating operations of the air bag
Similarly, at the place where the assist grip is disposed, the door interferes with the assist grip, so that an opening angle of the door is insufficient sometimes. Also in this case, the rapid completion of the development and expansion is hindered.
Accordingly, an object of the present invention is to provide an air bag for a head protection air bag device which rapidly completes its development and inflation even when a door of an air bag cover has a part or parts hard to open.
The present invention is directed to an air bag in use for a head protection air bag device. The air bag is stored along the peripheral edge of the upper fringe of an opening on the indoor side in a state that the air bag is covered with a door of an air bag cover and folded. When receiving inflation gas, the airbag forcibly opens the door and develops and inflates downward so as to cover the opening. In a region of an inflating section to which gas for inflation flows, a plurality of thickness defining members, which couple a cabin-inside side wall with a cabin-outside side wall to make a thickness of the inflating section uniform, are arranged side by side in the front/rear direction, while extending in the vertical direction,
In a first air bag of the invention, the thickness defining member disposed near the unsmooth development part of the door is disposed such that the upper end thereof is located at a position lower than the upper end of the thickness defining member in a state that the air bag is developed flat.
In a second air bag of the invention, of a plurality of inflow ports between the upper ends of the thickness defining members or the upper end of the thickness defining member and the peripheral edge part of the inflating section, an opening width of the inflow port being located near the unsmooth development part of the door as viewed in the front/rear direction is larger than an opening width of each of the adjacent inflow ports as viewed in the front/rear direction in a state that the air bag is developed flat.
In the thus constructed air bag in use for the head protection air bag device, when gas for inflation is introduced into the inflating section, the air bag having been folded develops and expands downward from the peripheral edge of the upper fringe of the opening in such a way that the air bag presses the door of the air bag cover to open and brings out of its folded state. And, it covers the opening on the indoor side.
In the first air bag of the invention, the upper end of the thickness defining member, which is located at position lower than the thickness defining member adjacent thereto is disposed near of the unsmooth development part of the door of the air bag cover. Accordingly, an inflation part which expands in the front/rear direction in a region above the thickness defining member is also vertically expanded more largely by a volume corresponding to the dimension of the lowering of the upper end. As a result, a large force to forcibly open the unsmooth development part of the door is secured. For this reason, even when the unsmooth development part of the door interferes with another member at the time of its opening, it is rapidly and forcibly opened. This technical feature contributes reduction of the time for the air bag 15 to complete the development and expansion.
In the second air bag of the invention, the opening width of the inflow port (as viewed in the front/rear direction) located near the unsmooth development part is selected to be larger than the opening width of the inflow port adjacent thereto (as viewed in the front/rear direction) Therefore, a vertically expanding inflation part of the inflow port, which is located near the unsmooth development part, expands in the front/rear direction more largely than the expansion part of the inflow port adjacent thereto, which vertically expand, by a distance corresponding to the opening width of the inflow port. As a result, a large force to forcibly open the unsmooth development part of the door is secured. For this reason, even when the unsmooth development part of the door interferes with another member at the time of its opening, it is rapidly and forcibly opened. This technical feature contributes reduction of the time for the air bag 15 to complete the development and expansion.
Thus, the air bag for a head protection air bag device, which is constructed according to the present invention, is capable of rapidly completing its development and inflation even when a door of an air bag cover has a part or parts hard to open.
Features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with the attached drawings.